1. Field of the Invention
The present invention relates to an electronically coded switching system, such as may be used for a light or electrical appliance, mechanical door lock and the like. More particularly, the present invention relates to a self-powered electronic keypad device that generates one or more activation signals for a switch. Electrical power is generated by simultaneously deforming a piezoelectric element while pressing individual buttons and/or entering a code on an electronic keypad. When the correct code is entered, the electrical power may then be used to directly or through and RF transmitter-receiver pair to actuate a device, such as a solenoid or key pin to engage and disengage the lock, or perform some other command function.
2. Description of the Prior Art
Electronically coded mechanical switching systems are known in the prior art. In an electronically coded system, the operator punches a coded sequence of electrically readable buttons. When the proper sequence of buttons is entered, (as read by the system's circuitry), the circuitry actuates switch, such as an electrical or electromechanical positioner (e.g., a solenoid or relay).
Mechanical locking systems are also known in the prior art. In the prior art the locking systems comprise, basically, a mechanical dead bolt by which, when engaged, a door may be locked and by which, when disengaged, a door may be unlocked. Engagement and disengagement of the deadbolt may be controlled by a small releasable pin, which typically moves 0.050 inches (or less) from fully engaged to fully released positions. In an electronically coded switching system, the electromechanical positioner moves the releasable pin, which allows the deadbolt to be moved (or which prohibits deadbolt movement, depending on the system configuration). In other switching systems, a switch or relay may be activated to energize another electrical circuit or device such as a light or other electrical appliance
In order for this prior system to work, electrical power must be supplied to the electromechanical positioner. In some configurations electrical power must also be supplied to the electrical keypad. In any event, all such prior systems must be connected to an electrical power supply: either a battery or to house electricity. Battery power is undesirable because it is expensive, batteries need to be periodically replaced, and the voltage output from the batteries changes over use and over time.
The use of house electricity is undesirable because the system becomes inoperable when the building loses power. Also, the cost of hardwiring the system to the house electrical power is expensive. In this situation it is necessary to drill holes, run cable and mount junction boxes. Drilling holes and mounting junction boxes can be difficult and time consuming. Also, running electrical cable requires starting at an electromechanical positioner and/or keypad, and pulling cable through holes in the framing the service panel. Though simple in theory, getting cable to cooperate can be difficult and time consuming. Cable often kinks, tangles or binds while pulling, and needs to be straightened out somewhere along the run.
Thus, a problem with conventional electronically coded switching systems is that extensive wiring must be run both from the switch boxes to the lights and from the switch boxes to the power source in the service panels.
Another problem with conventional electronically coded switching systems is that the high voltage lines are present as an input to and an output from the keypad.
Another problem with conventional electronically coded switching systems is the cost associated with initial installation of wire to, from and between locking system components.
Another problem with prior wireless electronically coded switching systems is the cost and inconvenience associated with replacement of batteries.
Accordingly, it would be desirable to provide an electronically coded switching system that overcomes the aforementioned problems of the prior art.